#define _CRT_SECURE_NO_WARNINGS 

#include <queue>
class Solution {
public:
    int m, n;
    int dx[4] = { 0,0,1,-1 };
    int dy[4] = { 1,-1,0,0 };
    bool vis[1001][1001] = { 0 };
    int rotApple(vector<vector<int> >& grid) {
        m = grid.size(), n = grid[0].size();
        queue<pair<int, int>> q;
        for (int i = 0; i < m; i++)
        {
            for (int j = 0; j < n; j++)
            {
                if (grid[i][j] == 2)
                {
                    q.push({ i,j });
                }
            }
        }

        int ret = 0;
        while (q.size())
        {
            int sz = q.size();
            ret++;
            while (sz--)
            {
                auto [a, b] = q.front();
                q.pop();
                for (int i = 0; i < 4; i++)
                {
                    int x = a + dx[i], y = b + dy[i];
                    if (x >= 0 && x < m && y >= 0 && y < n && grid[x][y] == 1 && !vis[x][y])
                    {
                        vis[x][y] = true;
                        q.push({ x,y });
                    }
                }
            }
        }
        for (int i = 0; i < m; i++)
        {
            for (int j = 0; j < n; j++)
            {
                if (grid[i][j] == 1 && !vis[i][j])
                {
                    return -1;
                }
            }
        }
        return ret - 1;
    }
};